Thats just how it was recorded. Pages guitar on that track has been that way for nearly half a century. Its such an appealing tune in so may ways though that its "flaws" are often over-looked. Its those little subtle under-tones that give the tune its character, charm and is partially what makes it unique. I haven't heard that tune in nearly 25 years...LOL

And this is why have a guitarist on the boards is a good thing. Us technodweebs probably would've gone back and forth on this for another few pages.

Oh, you're talking about Stairway. I believe the noise you're hearing is the microphone they used to mic that guitar cabinet. It's not overdriven type distortion because the frequency is much too high to be the guitar. More like the microphone diaphragm physically being moved too much by the SPL.

You might find this interesting, it's a dissection of Stairway and a discussion of the recording techniques used for it's production.

Taken from that site: The fanfare at 5:35 marks the end of Mr. Nice Guy. Page has three guitars spread across the field -- twelve-strings on the outside and a six in the middle. Notice the distortion here? The clicky noises that happen with each strum? I really doubt that was intended. That sounds to me as the the preamps in the mixing board overloaded, but I find it hard to believe Page or Andy Johns wouldn't have noticed that while they were tracking. It's possible that the distortion happened somewhere further down the line, or it's even possible that Page intended it (although I really doubt it). I can tell you that the same distortion exists on the vinyl, so it's not a CD error.

Yeah definitely check your source file. There is so much 'do it yourself' these days in the music industry that sometimes mistakes get through.

Anybody listened to Foster the People? There is some distortion on a couple of tracks on that album.

If it's on the guitar part, then more than likely it was their amplifier. Guitarists rarely direct box into a recording sesison. They use their amplifier, and put a mic in front of it to record the output. If there is a crackle from the amp, the crackle gets recorded and makes it all the way to your ears.

Now if you ever suspect it's not the track, as Obo suggested, frequency sweep to try and find obvious problems. A big problem I have had on DT880s is hair getting into the driver capsule and rattling on some bass notes. Beyerdynamic put a 1/4" (2mm) piece of very thick felt in between the driver and the foam ear piece, yet my short stiff little hairs some how manage to work themselves all the way through. I clean them monthly now to prevent the need for more open heart surgery.

The other common cause of distortion or crackling from a driver are dimples and dents.

Headphones are constructed with as thin and lightweight a driver material as possible. Usually it's some kind of plastic and since thin plastic is pretty floppy, they will mold curves and folds into it in order to make it stiffer and support itself. It looks nothing like a speaker cone anymore, it's full of rings, dimples, curves, etc. Anyway sometimes for various reasons one of these curves might get a wrinkle in it and that wrinkle will cause a crackling sound on certain frequencies. Depending on the construction of your headphone you may or may not be able to disassemble and expose the driver surface to pull those dimples out with a little masking tape. Sometimes the solution is as simple as blowing very gently on the driver.

It happens consistently (and repeatably) at the same point in the song... and it happens in both the left and right channels (c'mon, spontaneous failure of the same nature in both drivers?)... and frequency sweeps don't highlight the issue at all. It all kinda points to there being some kind of fault elsewhere in the signal path right?

Just sayin' - probably not a messed up driver.

Yeah, I agree with that, and that's why I wanted to point at the track itself as being botched - but if Logic isn't showing nasty peaks over those samples, then what else is there to point at? If it were the player/decoder the issue would "move", if it were the amplifier/DAC the issue would be more random, if it were the driver the issue would be more random, etc. Let's see what the dropbox'd track shows though.